OsbZIP65 enhances cold tolerance in rice by regulating ROS scavenging and carbohydrate metabolism

Cold stress limits rice productivity, yet how transcriptional regulation coordinates antioxidant defense and carbohydrate adjustment remains poorly understood. Here, we identified Group S bZIP transcription factor OsbZIP65 as a positive regulator of chilling tolerance. OsbZIP65 was rapidly induced by chilling and functioned as a nuclear transcriptional activator. Its overexpression enhanced survival and alleviated membrane injury, whereas knockout increased chilling sensitivity. OsbZIP65 bound G-box-containing promoter regions of OsGSTU6 , OsGR3 , and OsAGPS1 , activating the first two and repressing the latter, with these effects enhanced by chilling. Accordingly, OsbZIP65 promoted antioxidant capacity and soluble sugar accumulation while reducing reactive oxygen species and starch levels. These findings reveal a regulatory mechanism linking antioxidant defense and carbohydrate adjustment and identify OsbZIP65 as a potential target for improving chilling tolerance in rice